javascript - Select from two strings where they differ -

my page receives 2 strings:

var string1 = "_some_specification_abc_defgh_end_code"; var string2 = "_some_specification_34_kj_w7_end_code"; 

and want take differ display later title

function selectrelevantinfo (string1, string2) {     // don't know if regex here }; 

it should give abc_defgh string1 , 34_kj_w7 string2.

how can achieve it? in advance.

here's attempt, few tests make sure when prefix/postfix non-existent, or if both strings, etc.

it's similar in spirit pablo's code, in searches front , of strings, rather using indexof @ each iteration (accidentally quadratic), scalar character comparisons. function return object containing prefix , postfix both input strings stripped of these.

function findprepostfix(a, b) {    var minlength = math.min(a.length, b.length);      // important initialization , prefix search    var prelen = minlength;    (var = 0; < minlength; i++) {      if (a[i] !== b[i]) {        prelen = i;        break;      }    }      // similar search postfix search plus important initialization    var postlen = minlength - prelen;    (var = 0; < minlength - prelen; i++) {      if (a[a.length - - 1] !== b[b.length - - 1]) {        postlen = i;        break;      }    }      return {      : a.substring(prelen, a.length - postlen),      b : b.substring(prelen, b.length - postlen),      prefix : a.substring(0, prelen),      postfix : a.substring(a.length - postlen, a.length)    };  }    function display(a, b) {    $("body").append("<p>“" + + "” vs “" + b + "”: <tt>" +                     json.stringify(findprepostfix(a, b)) + "</tt></p>");  }  // display = function(a, b) { console.log(findprepostfix(a, b)) };    display('_some_specification_abc_defgh_end_code',          '_some_specification_34_kj_w7_end_code');    display("abc123", "123");  display("abc", "abc123");    display("abc", "def");  display("abc", "abc");

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